base/memory/ref_counted_delete_on_message_loop.h

   1 // Copyright 2013 The Chromium Authors. All rights reserved.
   2 // Use of this source code is governed by a BSD-style license that can be
   3 // found in the LICENSE file.
   4
   5 #ifndef BASE_MEMORY_REF_COUNTED_DELETE_ON_MESSAGE_LOOP_H_
   6 #define BASE_MEMORY_REF_COUNTED_DELETE_ON_MESSAGE_LOOP_H_
   7
   8 #include "base/location.h"
   9 #include "base/logging.h"
  10 #include "base/memory/ref_counted.h"
  11 #include "base/message_loop/message_loop_proxy.h"
  12
  13 namespace base {
  14
  15 // RefCountedDeleteOnMessageLoop is similar to RefCountedThreadSafe, and ensures
  16 // that the object will be deleted on a specified message loop.
  17 //
  18 // Sample usage:
  19 // class Foo : public RefCountedDeleteOnMessageLoop<Foo> {
  20 //
  21 //   Foo(const scoped_refptr<MessageLoopProxy>& loop)
  22 //       : RefCountedDeleteOnMessageLoop<Foo>(loop) {
  23 //     ...
  24 //   }
  25 //   ...
  26 //  private:
  27 //   friend class RefCountedDeleteOnMessageLoop<Foo>;
  28 //   friend class DeleteHelper<Foo>;
  29 //
  30 //   ~Foo();
  31 // };
  32
  33 template <class T>
  34 class RefCountedDeleteOnMessageLoop : public subtle::RefCountedThreadSafeBase {
  35  public:
  36   RefCountedDeleteOnMessageLoop(
  37       const scoped_refptr<MessageLoopProxy>& proxy) : proxy_(proxy) {
  38     DCHECK(proxy_.get());
  39   }
  40
  41   void AddRef() const {
  42     subtle::RefCountedThreadSafeBase::AddRef();
  43   }
  44
  45   void Release() const {
  46     if (subtle::RefCountedThreadSafeBase::Release())
  47       DestructOnMessageLoop();
  48   }
  49
  50  protected:
  51   friend class DeleteHelper<RefCountedDeleteOnMessageLoop>;
  52   ~RefCountedDeleteOnMessageLoop() {}
  53
  54   void DestructOnMessageLoop() const {
  55     const T* t = static_cast<const T*>(this);
  56     if (proxy_->BelongsToCurrentThread())
  57       delete t;
  58     else
  59       proxy_->DeleteSoon(FROM_HERE, t);
  60   }
  61
  62   scoped_refptr<MessageLoopProxy> proxy_;
  63
  64  private:
  65   DISALLOW_COPY_AND_ASSIGN(RefCountedDeleteOnMessageLoop);
  66 };
  67
  68 }  // namespace base
  69
  70 #endif  // BASE_MEMORY_REF_COUNTED_DELETE_ON_MESSAGE_LOOP_H_